Band-To-Band Optical Pumping in Solids and Polarized Photoluminescence

Band-to-band optical pumping of spin-polarized conduction electrons is demonstrated in p-type GaSb at 4.2^∘{}K by measurement of the degree of polarization of the photoluminescence. Significant electronic polarization [42 (±{}8)%] is achieved, and experiments with a weak transverse magnetic field yield the electronic lifetime τ=6.0(±0.7)×10^-9 sec of the photocreated electrons.